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06-13-2009, 10:02 PM   #16

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Quote:
 Originally Posted by Yoyizit Plotting gauge# vs. the log of (1/thickness in inches) gives a straight line on an Excel graph so it is some sort of reciprocal relationship. It's gauge# =~ 24.4[log(1/thkness)] - 12.2
So whats the inch thickness of a 7/0 gauge.

06-14-2009, 07:43 AM   #17
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Quote:
 Originally Posted by Ron6519 Then they should start a, "Brain Injury Forum." Here, let me start it off: "I have this screw with a slot and another screw with an ,"X". Is the "X" for xterior? Ron
I don't think you should be cluttering up this forum with your personal

thoughts on Gomer. It's off topic. Now either cool it or begone.

06-14-2009, 09:41 AM   #18
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Quote:
 Originally Posted by beenthere So whats the inch thickness of a 7/0 gauge.
"That does not compute!"

 06-14-2009, 09:48 AM #19 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,604 Rewards Points: 8,194 So it didn't work to tell you how thick in inches a 7 ought guage metal would be?
06-14-2009, 10:38 AM   #20
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Quote:
 Originally Posted by beenthere So it didn't work to tell you how thick in inches a 7 ought guage metal would be?
No, because the numbering system changes to avoid negative gauge numbers, same as the wiring AWG system.
http://en.wikipedia.org/wiki/American_wire_gauge

But if you tell me the thickness of 7/0 I can use the formula to tell you what negative gauge number it "should" have.

Maybe, way early on, they couldn't make thick wires so they put the 0 point at the thickest wire they could make. Then, as the technology improved, they wanted to keep the old system and just patch it by using multiple zeroes to indicate wires thicker than 0.

 06-14-2009, 10:44 AM #21 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,604 Rewards Points: 8,194 I'll give you an easy one first. How thick in inches is a 3 gauge metal.
06-14-2009, 11:17 AM   #22
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Quote:
 Originally Posted by beenthere I'll give you an easy one first. How thick in inches is a 3 gauge metal.
gauge# =~ 24.4[log(1/thkness)] - 12.2
so (#+12.2)/24.4 = log (1/thkness)
so 10^[(#+12.2)/24.4] = 1/thkness = A
so thkness = 1/A

3+12.2 = 15.2
15.2/24.4 = 0.623
A = 4.20
thkness = 0.238"

I think I'll start drinking rather early, today. . .

And, I inherited a bunch of old magazines yesterday, one of which told me that 6 BTU/sq. ft./HDD is "average", so my heat loss samples [previously published on this Forum!] must be representative of the general population of houses in North America.

We are definitely having fun this fine Sunday morning.

Last edited by Yoyizit; 06-14-2009 at 11:22 AM.

 06-14-2009, 11:24 AM #23 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,604 Rewards Points: 8,194 3 gauge US standard is .2500" thick. Manufacturers standard its .2391" thick. .238 would be somewhere between a 3 and a 4 gauge. Back to your spread sheet. PS: 7/0 is .5" thick.
06-14-2009, 05:03 PM   #24
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Quote:
 Originally Posted by beenthere 3 gauge US standard is .2500" thick. Manufacturers standard its .2391" thick. .238 would be somewhere between a 3 and a 4 gauge. Back to your spread sheet. PS: 7/0 is .5" thick.
7/0 should be -4.85, so I'd say -5 gauge.

One reason my answer is off is perhaps that, out of laziness, I only carried two significant figures when I derived the formula; the rule of thumb is to carry two more significant figures than you want in your final answer.
For your 4 significant figures I should have carried 6, so my 24.4 should have been 24.????

100(238/250) = 95% accuracy

100(238/239) = 99.6% accuracy

I would say that if my, or any, formula predicts the correct gauge number more times than not it's valid in a practical sense. The NIST would demand more than this but this ain't the NIST!
I've seen forum posters who couldn't determine a wire gauge, given a wire diameter. And neither could electricians for the same reason: the gauge number system has become a bit ambiguous.

If my formula is not accurate enough for a Forum then the real formula is more complex than the one I derived {Lawd help us!} or I didn't carry enough significant figures.

I gotta' say, Mr. B, that you are forcing me to sharpen my reasoning skills, and for that I'm thankful.
You're also helping me sharpen my writing skills, which I thought were adequate until I got onto Internet forums.

Last edited by Yoyizit; 06-14-2009 at 05:09 PM.

 06-14-2009, 06:32 PM #25 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,604 Rewards Points: 8,194 You can't rely on statistics and saying its acurate enough. When you have a spec sheet that says a gauge of X. Telling the inspecter, or engineer that its close enough, doesn't count. But does get you to pull it out, and redo it. With the proper gauge/thickness. Which is a big lost of money. Since the OP wanted to know the correlation. If he used one that is inaccurate. And was doing inspected work. He could lose 1000's of dollars on a job. Thats why anybody that does mechanical work, has reference books to look up various mechanical specs. Or, learns real quick to get them. Statistics prove that if you get caught cutting corners, and have to constantly redo your work because of it. You will lose more money then you make. So reference books are a cheap investment.
06-14-2009, 07:29 PM   #26
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Quote:
 Originally Posted by gomerpyle anyone know what the relationship is ?
Anybody else want to proffer a relationship? Going once, going twice. . .

06-15-2009, 10:06 PM   #27

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Quote:
 Originally Posted by Yoyizit Anybody else want to proffer a relationship? Going once, going twice. . .
Do you want a hint.

I don't want to weight you down.

 06-15-2009, 10:24 PM #28 Member   Join Date: Oct 2008 Location: Suburbs of Detroit Mi Posts: 3,704 Rewards Points: 2,000 F. E. What a maroon.
 06-17-2009, 05:05 PM #29 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,604 Rewards Points: 8,194 The relationship. Is the weight.
06-17-2009, 05:18 PM   #30
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Quote:
 Originally Posted by beenthere The relationship. Is the weight.
Then you have to specify a density.

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